1. Field of the Invention
This invention relates to a CMOS integrated circuit device and a method for inspecting same.
2. Description of the Related Art
In general, a decrease in threshold value of MOSFET increases the current driving power of the MOSFET, hence increases the operation speed of the circuit, and can realize a high-performance LSI accordingly. Otherwise, when the source voltage is decreased to save the consumption power, low power consumption is attained by decreasing the threshold value of MOSFET at no cost of the operation speed of the circuit.
An inspection method monitoring the static power source current to reject defective products is widely used for inspection of CMOS integrated circuits containing CMOS circuits having p-channel MOS transistors and n-channel MOS transistors. This is a method for measuring the power source current under a H or L signal being introduced to the input, to reject chips where a current larger than a predetermined value flows, regarding the phenomenon as an indication of a certain kinds of defects. This method relies on the nature of CMOS circuits that, under no change in the input (static condition), no power source current (static power source current) should flow in CMOS circuit.
However, when the threshold value is increased, the sub-threshold current of MOSFET increases, and a large static power source current flows even in non-defective chips. This results in decreasing the reliability of inspection, and leads to more defective products being mixed with acceptable products in market, or to the need for an additional inspection cost to prevent mixture of defective products.